Disclaimer: I am not a safety expert; this blog post is meant to give you a glimpse of the aspects to consider when you plan to design a kids fashion collection. It's meant for general guidance purpose and should not be considered or used as a substitute for any legal advise.
If you are planning to start a children's clothing collection, it's very important that you make sure that the clothing pieces are safe. Every country has their own regulations but here are some aspects to consider, depending the category. In fact, there are companies specialized in testing and proofing your products.
That babies and kids have very sensitive skin is a fact. That's why the material choice is very important when designing. Make sure the fabric composition and processing has no harming chemicals. The most skin-friendly material is organic cotton for example, but most of the pajamas are made out of flame retardant materials. Think also about possible scratchy labels! You can choose to have a printed size label instead, for example.
shape and form
Another aspect to consider is the shape and the form of the garment, for example the neck opening stretch and the dimensional stability. This means, does the piece of clothing stretches or shrinks after washing? One common thing I see is when the side seam line comes to the front in a wonky line. This happens mostly when the manufacturer wants to save fabric and doesn't place the pattern in the right thread direction position.
The most common examples of physical safety aspects to consider are buttons and snaps right attachment as well as trims and appliqués attachment (chocking hazard), sharp points and edges (injuries), zippers without protection (kids can get their skin caught by the zipper). I remember few years ago, we had to redesign a zipper pull tab for a client. It had the shape of a star, so 5 pointy edges that can cause injuries and we ended up combining the start shape within a circle. Other common example is cords and drawstrings, since they represent a hazard of strangulation in babies and kids.
Make sure you contact your local authorities regarding children's clothing safety. I would be glad to help you design a beautiful, healthy and safe collection for your clients.